*{
    margin: 0;
    padding: 0;
}

ul {
    list-style: none;
}

img{
    cursor: pointer;
}

#banner{
    width: 600px;
    height: 737px;
    margin: 100px auto;
    overflow: hidden;
    position: relative;
}

ul li {
    width: 600px;
    height: 737px;
}

#banner ul li img{
    width: 100%;
    height: 100%;
}

#banner span{
    width: 50px;
    height: 100px;
    margin-top: -50px;
    background: #ccc;
    opacity: 0.5;
    font-size: 50px;
    line-height: 100px;
    text-align: center;
    cursor: pointer;
}
#left{
    position: absolute;
    top: 50%;
    left: 0;
}

#right{
    position: absolute;
    top: 50%;
    right: 0;
}